Remarkable Image of Cometary Globule CG4 Captured by Large Telescope

Remarkable Image of Cometary Globule CG4 Captured by Large Telescope


An impressive image of the cometary globule CG4 has been captured by the ESO’s Very Large Telescope (VLT). Although their name associates them with comets, cometary globules are not at all related to comets and are actually a type of nebula. It is in fact a subtype of Bok globule, which is very dense, very compact and very cold nebula. Studying these globules is very difficult as they emanate no light and often appear as dark patches in the sky. Although they are some of the coldest objects of the universe, a very warm core often burns inside, which might be a forming star or multiple stars.

The cometary globule CG4 is also known as God’s Hand and its one side has been blown outwards forming a long tail similar to a comet. It is one of the many cometary globules located in the Gum Nebula and all of them have tails which trail away from the Vela supernova remnant. The tails might have formed due to the exploding star. There is another hypothesis behind its shape, according to which, the stellar winds and ionising radiation from very hot, very large OB stars nearby have caused this shape.

The globule is usually very faint and is located in the constellation of Puppis. It is composed of very dark and very dense material. Image captured by European Southern Observatory’s Very Large Telescope reveals that its head resembles a gaping mouth and is located 1.5 light-years across while its tail extends eight light years behind. The head of CG4, made up of thick cloud of gas and dust, is not glowing with its own light in the image; instead it is illuminated by the light of nearby stars. CG4 is gradually eroding due to the radiations from nearby stars but it is still maintaining its role as a stellar nursery and new stars are forming in its depths.

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  • David Carlson

    This is suggested to be a gravitationally-bound ‘dark matter’ (Bok) globule on a disk-crossing halo orbit that ‘decloaked’ in the galactic plane by the intense radiation from nearby OB supergiants which have sublimed the most volatile components of its icy chondrules, rendering it temporarily opaque and thus visible. If it survives the disk crossing without condensing any new stars, the luminous metallicity will ‘snow out’ at bitterly cold temperatures of around 10 Kelvins, sequestering the stellar luminosity into icy chondrules, leaving behind molecular hydrogen and helium which is invisible below the ultraviolet range and thus dark.

    But this cometary globule may not survive the disk crossing since volatilized stellar metallicity lowers the speed of sound, promoting Jeans instability within densified cores. In this way, (super)giant stars can nucleate new star formation within dark-matter Bok globules.

    ‘Reionization’ of the universe may be fossil radiation from a major phase change of the universe which occurred inside gravitationally-bound proto-galaxies, 150 million years to 1 billion years after the Big Bang, condensing the vast majority of the hydrogen and helium continuum into gravitationally-bound (Bok) globules. Endothermic ionization of hydrogen promoted nearly-isothermal gravitational collapse in an ALMOST EXACT analogy of the endothermic ionization of hydrogen which promotes gravitational collapse inside a protostar today to form its ‘second hydrostatic core’ (SHSC) (Larson 1969). Thus primordial globules are suggested to be the ALMOST EXACT equivalent of protostars today, with greater mass offsetting higher ambient temperature in the early universe.

    The largest globules (300+ solar masses?) in the early universe immediately collapsed into Population III stars, the first stars in the universe. Surviving Bok globules have cooled to become the ‘coldest objects in the natural universe’ because they’re the oldest objects in universe.

    Finally, WIMPs, axions, sterile neutrinos et al. can not explain the ‘cuspy halo problem’ absence of dark matter in galactic bulges and globular clusters, but globule dark matter requires it, converting to stars and luminous gas in high density regions of galaxies, and sometimes such as this in the galactic plane.

    Bok globules = cold dark matter reservoirs of galactic halos